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Falco, John; Barbanell, Patricia; Newman, Dianna L.; Dewald, Suzanne

doi:10.4018/9781591405917.ch014

Cited by 40 publications

(51 citation statements)

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“…The derived values for H 0 vary simply as 1/l max . Though the error bars are considerable, the plausible assumptions we have made yield results for H 0 that agree generally with the range spanned by current measurements (Schechter et al 1996;Giovanelli et al 1996;Sandage & Tammann 1996;Kim et al 1997;Falco et al 1997;Holzapfel et al 1997), with the unified model giving higher values. This in turn suggests that our model and input assumptions are in fact reasonable.…”

Section: Cosmological Parameterssupporting

confidence: 82%

Constraining Ω₀with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Buchalter¹,

Helfand²,

Becker³

et al. 1998

ApJ

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In previous attempts to measure cosmological parameters from the angular size-redshift (θ-z) relation of double-lobed radio sources, the observed data have generally been consistent with a static Euclidean universe, rather than with standard Friedmann models, and past authors have disagreed significantly as to what effects are responsible for this observation. These results and different interpretations may be due largely to a variety of selection effects and differences in the sample definitions destroying the integrity of the data sets, and inconsistencies in the analysis undermining the results. Using the VLA FIRST survey, we investigate the θ-z relation for a new sample of double-lobed quasars. We define a set of 103 sources, carefully addressing the various potential problems which, we believe, have compromised past work, including a robust definition of size and the completeness and homogeneity of the sample, and further devise a self-consistent method to assure accurate morphological classification and account for finite resolution effects in the analysis. Before focusing on cosmological constraints, we investigate the possible impact of correlations among the intrinsic properties of these sources over the entire assumed range of allowed cosmological parameter values. For all cases, we find apparent size evolution of the form l ∝ (1 + z) c with c ≈ −0.8 ± 0.4 which 1 ari@astro.columbia.edu 2 djh@astro.columbia.edu 3 bob@igpp.llnl.gov 4 rlw@stsci.edu is found to arise mainly from a power-size correlation of the form l ∝ P β (β ≈ −0.13 ± 0.06) coupled with a power-redshift correlation. Intrinsic size evolution is consistent with zero. We also find that in all cases, a subsample with c ≈ 0 can be defined, whose θ-z relation should therefore arise primarily from cosmological effects. These results are found to be independent of orientation effects, though other evidence indicates that orientation effects are present and consistent with predictions of the unified scheme for radio-loud active galactic nuclei. The above results are all confirmed by non-parametric analysis.Contrary to past work, we find that the observed θ-z relation for our sample is more consistent with standard Friedmann models than with a static Euclidean universe. Though the current data cannot distinguish with high significance between various Friedmann models, significant constraints on the cosmological parameters within a given model are obtained. In particular, we find that a flat, matter-dominated universe (Ω 0 = 1), a flat universe with a cosmological constant, and an open universe all provide comparably good fits to the data, with the latter two models both yielding Ω 0 ≈ 0.35 with 1σ ranges including values between ∼ 0.25 and 1.0; the c ≈ 0 subsamples yield values of Ω 0 near unity in these models, though with even greater error ranges. We also examine the values of H 0 implied by the data, using plausible assumptions about the intrinsic source sizes, and find these to be consistent with the currently accepted range of values. We dete...

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Section: Cosmological Parameterssupporting

confidence: 82%

Constraining Ω₀with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Buchalter¹,

Helfand²,

Becker³

et al. 1998

ApJ

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“…While it is intriguing that our results are roughly consistent with those seen in these two independent surveys done at different wavelengths, we remain cautious for now since the effect is only seen in our faintest bins. Other large, contiguous surveys now underway (Dey & Jannuzi 1997, Falco 1997 should provide an important check on this result. We note that the constraints on r o and ǫ discussed above do not change if we exclude the two faintest points from the analysis.…”

Section: Dependence Of the Slope On Magnitudementioning

confidence: 80%

Clustering at High Redshift: Precise Constraints from a Deep, Wide‐Area Survey

Postman

Lauer

Szapudi

et al. 1998

ApJ

129

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We present constraints on the evolution of large-scale structure from a catalog of 710,000 galaxies with I AB ≤ 24 derived from a KPNO 4m CCD imaging survey of a contiguous 4 • × 4 • region. The advantage of using large contiguous surveys for measuring clustering properties on even modest angular scales is substantial: the effects of cosmic scatter are strongly suppressed. We provide highly accurate measurements of the two-point angular correlation function, ω(θ), as a function of magnitude on scales up to 1.5 • . The amplitude of ω(θ) declines by a factor of ∼ 10 over the range 16 ≤ I ≤ 20 but only by a factor of 2 − 3 over the range 20 < I ≤ 23. For a redshift dependence of the spatial correlation function, ξ(r), parameterized as ξ(r, z) = ( r ro ) −γ (1 + z) −(3+ǫ) , we find r o = 5.2 ± 0.4h −1 Mpc, and ǫ > ∼ 0 for I ≤ 20. This is in good agreement with the results from local redshift surveys. At I > 20, our best fit values shift towards lower r o and more negative ǫ. A strong covariance between r o and ǫ prevent us from rejecting ǫ > 0 even at faint magnitudes but if ǫ > 1, we strongly reject r o < ∼ 4h −1 Mpc (co-moving). The above expression for ξ(r, z) and our data give a correlation length of r o (z = 0.5) ≈ 3.0± 0.4h −1 Mpc, about a factor of 2 larger than the correlation length at z = 0.5 derived from the Canada-France Redshift Survey (CFRS; Le Fevre et al. (1996)). The small volume sampled by the CFRS and other deep redshift probes, however, make these spatial surveys strongly susceptible to cosmic scatter and will tend to bias their derived correlation lengths low. Our results are consistent with redshift distributions in which ∼ 30 − 50% of the galaxies at I = 23 lie at z > 1. The best fit power law slope of the correlation function remains independent of I magnitude for I ≤ 22. At fainter limits, there is a suggestive trend towards flatter slopes that occurs at fluxes consistent with similar trends seen by Neuschaffer & Windhorst (1995) and Campos et al. (1995). The galaxy counts span 11 magnitudes and provide an accurate calibration of the galaxy surface density. We find evidence for mild galaxy evolution -about 1 mag of brightening or a doubling of the density by I = 23 relative to an Ω o = 1 no evolution model; about 0.5 mag of brightening or a factor of 1.5 increase in surface density relative to an open model. Our galaxy counts agree well with those from the HDF survey and, thus, argue against a significant inclusion of sub-galactic components in the latter census for I < 24.

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“…Small but nonzero differential reddening was also detected for three other lenses (HE1104-1805, H1413+117 and B1422+231). The lensed quasars SDSS0246-0825, HS0810+2554, FBQ1633+3134 and SDSS1138+0314 were not part of the sample studied by Falco et al (1999). We studied the latter object in §2.1 and concluded images B and C did not show evidence for differential reddening between them, but there is no information in this regard for the other three quasars.…”

Section: IV Compared To Hα and Hβmentioning

confidence: 96%

“…Reddening by the lens galaxy will typically vary between quasar images. Falco et al (1999) studied most of the objects in our sample and found that only two of them showed significant differential reddening: SBS0909+523 (∆E(B − V ) = 0.2 mag for image B with respect to A, see also Appendix A) and Q2237+0305 (∆E(B − V ) = 0.18 and 0.17 mag for images C and D with respect to A). Small but nonzero differential reddening was also detected for three other lenses (HE1104-1805, H1413+117 and B1422+231).…”

Section: IV Compared To Hα and Hβmentioning

confidence: 99%

Black Hole Mass Estimates Based on C Iv Are Consistent With Those Based on the Balmer Lines

Assef

Denney

Kochanek

et al. 2011

ApJ

148

172

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-Using a sample of high-redshift lensed quasars from the CASTLES project with observed-frame ultraviolet or optical and near-infrared spectra, we have searched for possible biases between supermassive black hole (BH) mass estimates based on the C iv, Hα and Hβ broad emission lines. Our sample is based upon that of Greene, Peng & Ludwig, expanded with new near-IR spectroscopic observations, consistently analyzed high S/N optical spectra, and consistent continuum luminosity estimates at 5100Å. We find that BH mass estimates based on the FWHM of C iv show a systematic offset with respect to those obtained from the line dispersion, σ l , of the same emission line, but not with those obtained from the FWHM of Hα and Hβ. The magnitude of the offset depends on the treatment of the He ii and Fe ii emission blended with C iv, but there is little scatter for any fixed measurement prescription. While we otherwise find no systematic offsets between C iv and Balmer line mass estimates, we do find that the residuals between them are strongly correlated with the ratio of the UV and optical continuum luminosities. This means that much of the dispersion in previous comparisons of C iv and Hβ BH mass estimates are due to the continuum luminosities rather than any properties of the lines. Removing this dependency reduces the scatter between the UV-and optical-based BH mass estimates by a factor of approximately 2, from roughly 0.35 to 0.18 dex. The dispersion is smallest when comparing the C iv σ l mass estimate, after removing the offset from the FWHM estimates, and either Balmer line mass estimate. The correlation with the continuum slope is likely due to a combination of reddening, host contamination and object-dependent SED shapes. When we add additional heterogeneous measurements from the literature, the results are unchanged. Moreover, in a trial observation of a remaining outlier, the origin of the deviation is clearly due to unrecognized absorption in a low S/N spectrum. This not only highlights the importance of the quality of the observations, but also raises the question if whether cases like this one are common in the literature, further biasing comparisons between C iv and other broad emission lines.

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E-Learning and Virtual Science Centers

Cited by 40 publications

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Constraining Ω₀with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Constraining Ω₀with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Clustering at High Redshift: Precise Constraints from a Deep, Wide‐Area Survey

Black Hole Mass Estimates Based on C Iv Are Consistent With Those Based on the Balmer Lines

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Cited by 40 publications

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Constraining Ω0with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Constraining Ω0with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Clustering at High Redshift: Precise Constraints from a Deep, Wide‐Area Survey

Black Hole Mass Estimates Based on C Iv Are Consistent With Those Based on the Balmer Lines

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Constraining Ω₀with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey

Constraining Ω₀with the Angular Size–Redshift Relation of Double‐lobed Quasars in the FIRST Survey